Embodiments of the invention include a system for supplying auxiliary power to a microprocessor or similar circuit during a loss of power.
Power losses occur for a variety of reasons. For example, a power loss can occur when a fuse blows, a battery connection is lost, or a ground fault occurs. During a power loss, microprocessors are generally unable to keep outputs asserted. Microprocessors are subsequently reset resulting in a loss functionality during the reset period that was being executed prior to the power loss. Of course, microprocessor and microprocessor-based controllers are used to control a variety of devices including various machines and vehicles.
Typical solutions to power loss problems in microprocessor-based systems include 1) using multiple surface mount devices (“SMD”) such as capacitors and 2) using a single, very large value, through-hole electrolytic capacitor at the voltage supply input. These solutions are generally costly and require a relatively large amount of printed circuit board (“PCB”) area. For example, using a single, very large value, through-hole electrolytic capacitor could involve unique manufacturing processes, which increases the cost of manufacturing such circuits. In some cases, a 220 μF capacitor is used and such a capacitor can generally keep power supplied to a microprocessor for approximately 3 ms. To provide power to the microprocessor for an extended amount of time, such as, for example, 20 ms, a capacitor having a size that is approximately ten times that of the 220 μF capacitor is required.